SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 44: Frustrated Magnets II
MA 44.5: Vortrag
Donnerstag, 30. März 2023, 16:15–16:30, HSZ 403
K2ReCl6: an unconventional Jahn-Teller system? — Alexandre Bertin1, Tusharkanti Dey1, Daniel Brüning1, Dmitry Gorkov1,2, Kevin Jenni1, Astin Krause1, Petra Becker3, Ladislav Bohatý3, Daniel Khomskii1, Thomas Lorenz1, and •Markus Braden1 — 1II. Physikalisches Institut, Universität zu Köln — 2Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München — 3Abteilung Kristallographie, Institut für Geologie und Mineralogie, Universität zu Köln
Antifluorite compounds of chemical formula K2MX6 (where M is a transition metal and X=Cl,Br) can exhibit various crystallographic phase transitions, often understood by the softening of rotary phonon modes of the ligand octahedra surrounding the central transition metal. Among this family, K2ReCl6 exhibits on cooling four distinct structural phases and may constitute a playground to investigate the interplay between spin-orbit coupling (SOC) and Jahn-Teller (JT) effect. The question whether one of the crystallographic phase transitions is JT driven will be tackled by presenting a detailed temperature dependent structural study of K2ReCl6 and of its non magnetic counterpart K2SnCl6 by means of powder and single crystal XRD. With neutron diffraction experiments and by taking the low temperature monoclinic symmetry into account, the magnetic structure was solved. Frustration is only partially lifted by the structural distortions and the magnetic order causes further symmetry reduction. Finally, the strong magneto-elastic effect seen in thermal expansion measurements will be discussed in terms of domain re-orientation and weak ferromagnetism.